Telephone receiver



K. SIEBEL TELEPHONE RECEIVER June 22 1926.

Filed Nov. 18, 1924 1mm Km AW M Patented June 22, 1926.

UNITED STATES 1,589,823 PATENT OFFICE.

KARL SIEIBEL, OF KIEL, GERMANY, ASSIGHOB TO THE FIRM: NEUFELDT & KUHNKE, BETBlEBsGEsELLficmT I. B. H., O! KIEL, GERMANY.

TELERHONB RECEIVER.

Application filed November 18, 1924, Serial Io. 750,564, and in Germanylovember 80, 1 923.

This invention relates to improvements in telephone receivers and has for its object to simplify the construction of telephones, thus reducing the manufacturing cost, without sacrificing the good quality of the telephones.

According to the invention a three pole magnet in form of a prism with two portions cut out from one longitudinal side is employed in connection with a magnetic diaphragm, .the two, external poles of the magnet either making contact. directly with the peripheral portion of the diaphragm or making contact with a thin ring of sheet-lron interposed between the diaphragm and such poles.

This construction possesses very good magnetic properties and is particularly favourable for the fitting on of the coil. Also, the magnet structure is capable of being produced very easily.

' An example of a telephone constructed in accordance with the invention is illustrated by the accompanying drawing, in which Figure 1 is a plan of a telephone recelver casing containing a three pole magnet constructed in accordance with these improvements.

Figure 2 is a section on the line A -B ct Figure 1 but in this section a polar rmg is shown in contact with the external poles and a diaphragm in contact with the ring.

1 is the case of the telephone, and 2 is the three-pole magnet, consisting of four laminae produced by" punching or stamping from sheet steel, thus rendering the manufacture easy. 3 and 4 are the external poles of like polarity, and 5 is the central pole of opposite polarity, this pole 5 being adapted for the mounting of a coil. V

,In Figure 2, 6 is a distance-ring of soft iron. in contact with the two external poles 3-and 4, the diaphragm? lying against the distance-ring. The iron-ring 6 is easily produced by punching or stamping. By this iron-ring the distance between the diaphragm and the pole 5 is exactly fixed, pro- .vided that the faces of the three poles 35 are level, which may be obtained easily by grinding top of the telephone-case with the magnet mounted in it.

The distance-ring 6 may of course be exchanged for two iron-plates, laid on the poles ground by one and the same operation. A

3 and 4, but this is not to be recommended as in this case devices must be provided for fastening the diaphragm around the Whole periphery. Also, the diaphragm may be placed directly in contact with the faces of the poles 3 and 4. In this case, the inner pole 5 mustbe shortened, for instance by appropnatemanipulation of the grinding disc or tool.

According to experience, the sensitiveness andreceiving quality of a telephone comprising these improvements equals and often surpasses similar qualities of telephones at present 1n use. The manufacturing costs are extremely low as compared with those of other telephones. The telephone-magnet, usually of a complicated shape, composed of several pieces, consists according to this in ventlon only of an assemblage of laminae, stamped out of sheet steel. Instead of the two coils heretofore commonly used, only one coil is necessary for the magnet hereinbefore 75 described. The manufacture of the telephone, especially in accordance with Figure 2, is quite simple, all poles of the magnet being level with the edge of the case and being ring 6 stamped out of thin sheet iron not only magnetically connects the external poles and the diaphragm, but at the same time serves to adjust the centre of the diaphragm in relation to the central pole.

1. A telephone having a casing containing a three ole magnet comprising a prismatic magnet ody recessed at two places on its' upper longitudinal side to form one central pole and two external poles, and amagnetic diaphragm having its peripheral portions in magnetic contact with the external poles of said magnet.

2. A telephone having a casing containing a three pole magnet comprising a prismatic magnet bodyrecessed at two places on its upperlongitudinal side to form one central pole and two external poles, a magnetic spacing ring covering the external poles and a magnetic diaphragm on said ring having magnetic contact with said poles at its peripheral portions thru said ring.

In testimony whereof I aflix my signature.

KARL SIEBEL. 

